Broker connection uses the heartbeat setting from app config unless set otherwise (#4148)

* broker connection uses the heartbeat setting from app config unless set otherwise

* test for broker heartbeat settings

* split long lines of code

celery/app/base.py

@@ -826,7 +826,7 @@ class Celery(object):
             port or conf.broker_port,
             transport=transport or conf.broker_transport,
             ssl=self.either('broker_use_ssl', ssl),
-            heartbeat=heartbeat,
+            heartbeat=heartbeat or self.conf.broker_heartbeat,
             login_method=login_method or conf.broker_login_method,
             failover_strategy=(
                 failover_strategy or conf.broker_failover_strategy

t/unit/app/test_app.py

@@ -786,6 +786,20 @@ class test_App:
         assert self.app.connection('amqp:////value') \
                        .failover_strategy == my_failover_strategy
 
+    def test_amqp_heartbeat_settings(self):
+        # Test default broker_heartbeat value
+        assert self.app.connection('amqp:////value') \
+                   .heartbeat == 0
+
+        # Test passing heartbeat through app configuration
+        self.app.conf.broker_heartbeat = 60
+        assert self.app.connection('amqp:////value') \
+                   .heartbeat == 60
+
+        # Test passing heartbeat as connection argument
+        assert self.app.connection('amqp:////value', heartbeat=30) \
+                   .heartbeat == 30
+
     def test_after_fork(self):
         self.app._pool = Mock()
         self.app.on_after_fork = Mock(name='on_after_fork')